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Oxidative cleavage of C(OH)−C bonds to afford carboxylates is of significant importance for the petrochemical industry and biomass valorization. Here we report an efficient electrochemical strategy for the selective upgrading of lignin derivatives to carboxylates by a manganese‐doped cobalt oxyhydroxide (MnCoOOH) catalyst. A wide range of lignin‐derived substrates with C(OH)‐C or C(O)‐C units undergo efficient cleavage to corresponding carboxylates in excellent yields (80–99 %) and operational stability (200 h). Detailed investigations reveal a tandem oxidation mechanism that base from the electrolyte converts secondary alcohols and their derived ketones to reactive nucleophiles, which are oxidized by electrophilic oxygen species on MnCoOOH from water. As proof of concept, this approach was applied to upgrade lignin derivatives with C(OH)‐C or C(O)‐C motifs, achieving convergent transformation of lignin‐derived mixtures to benzoate and KA oil to adipate with 91.5 % and 64.2 % yields, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Boosting cobalt-catalyzed ethanol steam reforming for hydrogen production. • Donation of electron density from concomitant O 2 2− to Co/La 0.25 Ce 0.75 O 1.88 catalyst. • Regulation of valence state and reducibility of Co catalysts via La doping in CeO 2. • Investigation of catalytic ESR reaction mechanism by in situ DRIFTS studies. Tuning the valence state and reducibility of Co active site in Co-based catalysts to improve catalytic performances is desirable for hydrogen production from ethanol steam reforming (ESR) reaction. In this work, we fabricate Co/La x Ce 1−x O 2−x/2 (x = 0.5, 0.25, 0.17) catalysts and investigate their catalytic performances for ESR reaction. Our studies manifest that the catalytic performances of Co-based catalysts have been effectively improved by La doping in CeO 2. Among the investigated catalysts, Co/La 0.25 Ce 0.75 O 1.88 exhibits the highest catalytic activity and durability, the hydrogen yield reaches as high as 80 % at ethanol conversion of 100 %, with an excellent durability during long-time (58 h) catalytic experiment. X-ray photoelectron spectroscopy (XPS) and hydrogen temperature programmed reduction (H 2 -TPR) studies demonstrate that the valence state and reducibility of the Co/La 0.25 Ce 0.75 O 1.88 are effectively regulated via donation of electron density from the concomitant peroxide anions in La 0.25 Ce 0.75 O 1.88 to the supported cobalt catalyst, the C C bond cleavage capability has been significantly enhanced to boost the hydrogen-production efficiency from ESR reaction. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies reveal that Co/La 0.25 Ce 0.75 O 1.88 shows a remarkable preference for producing C1 products, the Co species in low valence state and with high reducibility result in highly efficient C C cleavage and excellent catalytic durability. [ABSTRACT FROM AUTHOR]